title: Zebrafish bioassay-guided natural product discovery: isolation of angiogenesis inhibitors from East African medicinal plants.
abstract: Natural products represent a significant reservoir of unexplored chemical diversity for early-stage drug discovery. The identification of lead compounds of natural origin would benefit from therapeutically relevant bioassays capable of facilitating the isolation of bioactive molecules from multi-constituent extracts. Towards this end, we developed an in vivo bioassay-guided isolation approach for natural product discovery that combines bioactivity screening in zebrafish embryos with rapid fractionation by analytical thin-layer chromatography (TLC) and initial structural elucidation by high-resolution electrospray mass spectrometry (HRESIMS). Bioactivity screening of East African medicinal plant extracts using fli-1:EGFP transgenic zebrafish embryos identified Oxygonum sinuatum and Plectranthus barbatus as inhibiting vascular development. Zebrafish bioassay-guided fractionation identified the active components of these plants as emodin, an inhibitor of the protein kinase CK2, and coleon A lactone, a rare abietane diterpenoid with no previously described bioactivity. Both emodin and coleon A lactone inhibited mammalian endothelial cell proliferation, migration, and tube formation in vitro, as well as angiogenesis in the chick chorioallantoic membrane (CAM) assay. These results suggest that the combination of zebrafish bioassays with analytical chromatography methods is an effective strategy for the rapid identification of bioactive natural products.
authors.affiliation: Department of Pharmaceutical Sciences, University of Leuven, Leuven, Belgium. alexander.crawford@pharm.kuleuven.be
authors.forename: Alexander D
authors.initials: AD
authors.lastname: Crawford
authors.forename: Sandra
authors.initials: S
authors.lastname: Liekens
authors.forename: Appolinary R
authors.initials: AR
authors.lastname: Kamuhabwa
authors.forename: Jan
authors.initials: J
authors.lastname: Maes
authors.forename: Sebastian
authors.initials: S
authors.lastname: Munck
authors.forename: Roger
authors.initials: R
authors.lastname: Busson
authors.forename: Jef
authors.initials: J
authors.lastname: Rozenski
authors.forename: Camila V
authors.initials: CV
authors.lastname: Esguerra
authors.forename: Peter A M
authors.initials: PA
authors.lastname: de Witte
mesh_terms: D045784:Abietanes / Q000494:pharmacology; D000351:Africa, Eastern; D020533:Angiogenesis Inhibitors / Q000302:isolation & purification* / Q000494:pharmacology; D000818:Animals; D030801:Animals, Genetically Modified; D001681:Biological Assay / Q000379:methods*; D001688:Biological Products / Q000302:isolation & purification* / Q000494:pharmacology; D002478:Cells, Cultured; D002642:Chick Embryo; D031330:Coleus / Q000737:chemistry; D055808:Drug Discovery / Q000379:methods*; D004625:Embryo, Nonmammalian / Q000098:blood supply / Q000187:drug effects; D004642:Emodin / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D018919:Neovascularization, Physiologic / Q000187:drug effects / Q000502:physiology; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D010946:Plants, Medicinal / Q000737:chemistry*; D015027:Zebrafish / Q000196:embryology / Q000502:physiology
chemical_list: D045784:Abietanes; D020533:Angiogenesis Inhibitors; D001688:Biological Products; D010936:Plant Extracts; C560600:coleon A lactone; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D004642:Emodin